Poison Heart
by Rangergirl3
Summary: The castle has been corrupted, but one Paladin is in more danger than the others. Alternate ending to the episode 'Crystal Venom'. Because when you want to destroy something, you try to poison its heart. Also the sequel to my story 'Black Paladin'. Rated T for language and violence.


_For those who have read my story 'The Black Paladin', there is one detail I should have mentioned at the end of that story, especially given the events in this sequel._

 _In order to keep the series continuity of having a Galran prisoner in the castle, I mentally had Haxus be the only Galran who was not beamed out, and instead captured in the place of Sendak._

 _I imagine he was in the engine room when the others were beamed out and got caught by Coran before he realized what had happened to his comrades or could do any other damage to Team Voltron. Anyway, it keeps things streamlined for the purposes of this story._

 _I'm really sorry for any confusion. I realized I wanted to write something for this episode, but I wanted to try and keep as much of the original plot intact as possible so I can write what I want inside the original setting. Because a haunted castle, inner demons, and an exploding star is just too good of a setting to want to change. Anyway, enjoy. :-)_

 _Language and violence ahead. You have been warned._

Earlier, as they had been traveling to the Balmera, Shiro and Keith were training together against the Gladiator. Together, they succeeded in defeating the Level Three foe.

"You're pretty good at this, Keith," Shiro said as he wiped sweat off his forehead with his fist.

"Yeah," Keith said. He didn't want to brag or anything, especially as Shiro had probably taken on Level Three foes by himself in the arena. He didn't want to remind his friend of those experiences. He turned around and realized Shiro had come over to him.

"What's up?" he asked.

Shiro seemed to hesitate for a second, glancing back over his shoulder at the door to the training room. No one else was with them. Hunk was helping Coran prepare something edible for dinner, and Lance and Pidge were trying out the invisible maze exercise, with Allura supervising the last few adjustments to the new core crystal. It was just him and Keith.

"Listen, Keith," he said. "I've been…I'm…" He searched for words, but nothing seemed to come. He huffed out a breath and scratched the back of his neck. "I need to ask you to do something for me."

"Anything," Keith said at once. "Shiro, what is it? What's wrong?"

Shiro half-laughed and turned to look straight at Keith. "It's nothing…well, I should say it's nothing yet." He straightened his back and looked his old friend in the eye.

"You know how sometimes…I freeze up during battle?"

Keith nodded. "Flashbacks. It's to be expected."

Shiro gave a half-shrug. "Probably. But it's not just that. Sometimes I think - I think the Galra might try to take control of me. Use my abilities against the team."

Keith nodded again, trying to conceal the worry that had suddenly gripped his heart. Ever since the Head Druid's attempted brainwashing, he'd kept a close eye on Shiro. Not just because he wanted to help his friend, but because he thought something like that might happen. He had hated not telling Shiro what he feared, but he had a feeling Shiro had guessed what was on Keith's mind.

"The thing is," Shiro continued, "I wanted to ask you - to ask you to - um, well-"

"Stop you if it happens?" Keith asked. "Because you don't need to ask that. I wouldn't let you hurt anyone, or take Black over to them. I'd help you to regain control, and if I had to put you in a pod until we found a way to break their grip, I'd do it. I'd hate it, but I'd do it."

Shiro's mouth tightened, but not in anger. At least, not at Keith himself. It was anger at the thought of being someone else's plaything, a puppet that could harm or kill someone he cared deeply about. For a moment, Keith was afraid he'd said too much. Sometimes he did. But Shiro knew him well, and after a moment, his face relaxed a little and he gave Keith a half-grin.

"Good," he said. "I didn't know how you'd take that request."

"Oh, I hate the idea of fighting you," Keith said. "I really, _really_ hate it."

"But you could do it," Shiro said, a trace of seriousness still in his voice. "You might be the only one who could."

Keith felt his face settle into his customary half-frown. "Can we talk about something else? Anything else?"

Shiro nodded. "Right after I tell you this." He held Keith's gaze. "If the Galra take control, I want you to stop me. No matter what I say, no matter what I do, I want you to keep me from hurting anyone. Especially anyone on this team."

Keith gave a short, curt nod. "I would. I will. Just - come on, let's change the subject, okay?"

Shiro nodded again. "Okay."

A sudden beep from the speakers sounded, and Hunk's voice came over the comms system. "Dinner is served, people! Ten minutes till the most delicious dinner you've had yet - don't want to show up to save the Balmera on an empty stomach!"

Keith and Shiro glanced at each other. "Think he managed to make green goop palatable?" Shiro asked.

"Hunk's pretty talented in the food department," Keith answered.

Shiro grinned, looking more like his usual self. "Then let's go test that theory."

And they'd done it. Then They'd saved the Balmera, and now they were going to get information from Haxus.

But something had gone wrong. Horribly, horribly wrong.

A training bot nearly had nearly killed him, Lance had almost been sucked out an airlock, and Pidge and Hunk had been attacked in the kitchen by goop.

When Keith asked if anyone had seen Shiro, no one said yes. Something seemed to drop out of his stomach. Without waiting for any of the others to follow him, he turned and ran down towards the level where Shiro had been seen last.

When he got there, the others hard on his heels, he found Shiro near an empty pod.

"Where's Haxus?" he asked.

"I - I had to get him out of here - " Shiro said. His face was in shadows, his cybernetic hand pressed against the side of his head.

The others were behind him, asking questions, but all of Keith's attention was on Shiro.

"Shiro - what's - " Keith stopped mid-sentence.

Shiro was saying something, his voice tight, his face twisted in pain, and his eyes were closed, as if trying to shut out the dim light in the hallway.

"My head — it really hurts - "

Coran stepped forward, concern on his normally cheerful face. "I can help - Shiro, come on, let's get you - "

Keith grabbed hold of Coran's arm, holding him back. Something in Shiro's voice was different. Wrong.

 _Oh shit_.

"Shiro?" Keith asked again. The other Paladins sensed something wasn't right. For once, they were all quiet.

Shiro's face was still in shadow, but he'd opened his eyes, and there was a yellow glint to them. It was deeply unsettling. His voice - his voice was thready now, almost a whisper.

"Re…..reaaally….hurtssss…"

Keith felt something cold settle inside his heart. He took a step back, noticing that the others were doing the same.

The others.

He'd promised Shiro he'd protect them.

Feeling something break inside him, he drew his bayard and activated it. The sword hummed, and with that familiar sound, everything came into crystal clear focus.

"Coran," he said, and his voice was steel. "Get them out of here."

There were noises from the other Paladins, voices raised in concern, confusion, and fear, but he couldn't make out the words. All his attention was fixed on Shiro. The Black Paladin turned towards him, and his cybernetic hand was glowing purple. His irises were now Galran yellow, and he took a step towards Keith, who took a defensive stance. Shiro's mouth moved, and the next few words struck fear into Keith's marrow.

"Raaa…pid…Saa…"

 _Oh fuck._

With a sudden lunge to the side, Shiro struck at Coran, who's friendly face had gone ashen pale. A clash, a ringing, the shriek of tortured steel.

Keith had gotten between them just in time. His blade had deflected Shiro's hand, and the Black Paladin seemed to realize, just for an instant, what was happening. He took a half step back, and his eyes flickered back to their normal color. Sweat beaded his forehead, and fear radiated from him like a wave.

"Oh, God," he said, and his voice was unsteady. "Keith - Keith, I can't control it -"

He took two steps back again, his gaze darting between each of them. "Please — run - "

A spasm of pain crossed his face, and he doubled over, twisting away, his flesh hand clutching his head, almost falling to the ground.

Keith gritted his teeth, hating himself, and pressed his advantage. He kicked Shiro backwards, further away from the other Paladins. He tried to ignore the sound of pain Shiro made, the wrenching, gasping sound as he landed on his back and tried to get air back into his lungs.

He ignored the Paladins behind him, their cries of confusion and fear. Distantly, he heard a sliding, whispering sound and realized Coran had brought up a protective barrier, to keep the other three Paladins from interfering with what had to be done. Then footsteps, a single person coming up behind him.

Good. They had a better chance of containing Shiro if there were two of them.

Coran was a soldier too. He would help Keith do what was needed.

Shiro had gotten to his hands and knees now, and he was still trying to get air. Keith came closer, focusing on the pods behind Shiro. If he could somehow get him into one of those, he could at least keep Shiro contained and stationary until the Galran infection could be treated -

Then Shiro's eyes had flickered back to yellow, his head had tilted to one side, looking up at Keith, and his teeth were bared in a calculating smile.

" _Die, Paladin scum,"_ he spat. With a vicious lunge, he was right in front of Keith, and his glowing fingertips were coming at Keith's neck. It was clear whatever intelligence was in control intended to behead him, and move on to the others next.

Keith took advantage of these precious few seconds. He hated himself for this calculation. He hated being the one who had to do this.

With a scream, he turned to one side, bringing all his momentum behind his swing, and slashed. The glowing purple arm fell to the floor. For an instant, there was silence. Even behind the protective barrier, the other three Paladins had fallen silent. Everyone stayed perfectly still, mouths open, eyes staring.

No one could believe what had just happened.

Then a scream from the castle itself shook through the floors, the walls, the ceiling. It was a jagged, tortured sound. Everyone staggered as if struck, and Keith saw Coran dart past him, right at Shiro. With a sudden tackle, the Altean had pinned Shiro against the ground, Shiro's one remaining arm locked behind his back. Blood pulsed from where his cybernetic arm had been. Keith had sliced the arm off right below the shoulder. Flesh and bone showed through the wound, but not a single shred of Galran technology remained.

Shiro was screaming, trying to get free, his voice changing and altering, face contorted in rage, yellow eyes burning, staring at Keith with absolute hatred.

Then the yellow glare went out as if a switch had been flicked, and Shiro suddenly went still, his gaze going from Keith, with the dripping sword, to the three terrified teenagers behind the barrier wall Coran had raised as protection against him. Pidge, her fingers on the keyboard, caught mid-hack in her attempt to bring down the protective wall. Lance, beside her, bayard out and ready, but pointed at the floor now. Hunk, beside Lance, hands fisted and pressed up against the shimmering wall. They were all looking at him, and they were scared. They were scared of _him_.

He closed his eyes and let his forehead rest against the cold floor. He felt sick, and it had nothing to do with losing his arm a second time. That pain was almost welcome in comparison to what he felt at seeing those faces white with fear.

They would never trust him again. He'd tried to - he'd almost -

Keith and Coran exchanged glances, and from Keith's nod, Coran could tell the danger was over. All the same, he didn't release his grip immediately. Instead, he tried talking.

"Shiro, it's okay, we're here to help you. I've got to get you to a healing pod. Can I help you get there?"

All he got in reply was a weak nod. Coran relaxed his grip on Shiro's arm and adjusted so that he could help Shiro roll over, first onto his uninjured side, then onto his back. From out of the corner of his eye, Coran saw Keith kick the Galran arm into an adjoining airlock and hit the 'eject' button.

Good riddance.

Shiro's eyes were closed, but his breaths were harsh, almost wrenching. Sweat dripped down his neck, and his face was pale. Coran got one arm under his neck and helped him sit up. Shiro's balance was off, but Coran steadied him. He'd taken off his Altean jacket and used it as a makeshift bandage to staunch the flow of blood from the stump of his arm.

"Don't exert yourself," he said. "We'll do all the work. Stay as still as you can, okay?"

Keith came over and helped support Shiro's other side as they helped him to get to his feet.

"Don't walk," he said. "Just let us carry you. We have to keep your heart rate down."

As they started walking towards the door that led out of the level and towards the infirmary, the blood began to stain Keith's uniform, but he didn't flinch from it. His hands shook slightly, but his mouth was set into a firm line. His eyes were hard, but Coran could tell he was shaken badly from having to do what he'd done.

Shiro raised his eyes as they neared the door that lead out towards the infirmary. Lance, Pidge, and Hunk were still behind the protective barrier Coran had raised. They were going to have to pass by them.

What would he say to them? What _could_ he say?

"I'm sorry that I went Terminator on you, guys. Won't happen again."

Because how did he know it wouldn't?

God, they'd never trust him again. He'd lost them, almost as surely as if he'd killed Coran in that first attack.

As they came to the protective barrier, Coran deactivated it. Shiro expected the other three Paladins to retreat from him, to keep a safe distance. What he wasn't expecting was them to surge forward, faces set in deep concern.

"Oh my God, Shiro - are you okay?!" Pidge was frantic with worry, bobbing up and down, trying to keep out of the way but desperate to help at the same time. Her glasses were askew on her face, and she seemed about ready to cry.

"I can get the pod ready!" Lance declared, suddenly breaking away from the group and racing ahead. "Coran, the one I just cleaned should be primed and ready - I'll meet you all there - "

Hunk said nothing at first, but stayed only a few steps away while they traveled down the hallway. "The castle isn't safe - I should find Allura, get her back to the group-" he suddenly announced, as if he'd been trying to think of something useful he could do and this had just become clear to him as the most obvious way he could help. He brought out his bayard and began to turn down the hallway when an alarm began to sound.

Shiro felt Coran tense, and was just barely able to hear him say something about the ship making a warp jump before everything went fuzzy and indistinct. The last thing he heard was Keith, telling him to stay awake.

 _I'm sorry,_ Shiro tried to say. _I'm really sorry._

Keith felt Shiro sag forward and barely managed to keep him upright with Coran's help. He told Hunk and Pidge to get to the bridge and figure out what was going on while they got Shiro to the healing pod.

While they managed to escape the collapsing star, they did not make it out unscathed. The ship took some damage that necessitated a return to the Balmara for some much needed rest and repairs.

When the healing pod released Shiro, the entire team was waiting for him. The first thing Keith did was to present Shiro with a new arm, completely functional and made from the finest Altean technology.

Shiro managed a tired half-smile of thanks before the rest of the team encompassed him in a giant hug. Keith had not known of the incoming hug and was caught in the middle of it as well. He tried to break free, but he didn't know how to do it without elbowing past three people. He settled for trying something familiar.

"Lance - get OFF!" he growled, but it wasn't very heated.

"Nope nope nope - you get one too," Lance said. "It's part of being a family. We get through things together."

"Yeah we do," Hunk said. He was on the outside of the group hug, and he squeezed his adopted family a little bit tighter, not so hard as to hurt, but just hard enough where they could know how very much he loved them all.

Pidge made a sound of mixed agreement and slight annoyance. "You can't get out of it," she told Keith. Her face was very close to his elbow and one of her ears was pressed against Shiro's side. His heartbeat was familiar, and steady, and very comforting.

"I don't know what you call this," Coran said brightly from somewhere near Pidge, "But I like it!" He beamed at Allura, who's eyes were a little bit brighter than usual.

"Paladins," she said, after clearing her throat. "I just - wanted to thank you for - for everything. I don't say it enough, but you all mean a great deal to me."

Shiro blinked in surprise at her, but managed to say "Well, you mean a lot to us, too," before he had to tap out of the hug. The three youngest Paladins relaxed their grips, but stayed close to him, still hugging him.

"Guys…" he said. "Keith's beginning to get claustrophobic."

"Yes," Keith said. "I am." He elbowed Lance in the side, but it was really more of a light push. His mouth was slightly quirked into a reluctant half-smile. "Cut it out already."

"One more minute," Pidge said. "We really missed you. And we're really, really glad you're both okay."

Shiro sighed. "While we're all here, I just wanted to say - "

"- that you don't blame Keith for helping you get rid of your evil cybernetic arm. Yeah, we figured," Lance said. "I mean, let's never do that again if we can help it, but yeah, we figured."

Shiro blinked again and saw Keith's jaw drop open in surprise. "You did?" Keith asked. "Why didn't you guys say something?"

"We did," Hunk said soothingly. "But you were closeted in your room making that new arm for Shiro and it felt like you needed space. Also, you weren't really very receptive to any communication from us."

"It got to the point where I was going to try sending the mice in with messages through your vents," Pidge said. "But Coran said it was something you'd need to hear from us. And this has been the first time you've left your room since we escaped from the exploding star."

Finally, the hug ended. Keith broke free and darted to one side, leaving Shiro in the middle of the group. He muttered something about needing to go check on Red, but just before he left the room, he made eye contact with Shiro.

His old friend nodded at him, a silent acknowledgement of what had transpired, and a thank you.

Keith nodded back.

Everything would be fine. It'd all go back to normal.

Well, what passed for normal now.


End file.
